1. Field of the Invention
The present invention relates generally to displays. More particularly the invention concerns displays comprising an optical waveguide, a light source and a plurality of electromechanical picture elements.
2. Discussion of the Prior Art
Currently liquid crystal displays dominate the flat panel display market. Prior art liquid crystal displays typically comprise a backlight assembly for illumination, light polarizers, color and neutral density filters, and an active matrix liquid crystal layer with thin-film-transistor backplanes. The overall light efficiency of a typical prior art liquid crystal display (LCD) is below 10% mainly due to the fact that light from the backlight assembly has to pass several layers of polarizers, color and neutral density filters. A further problem with LCDs is the slow response time of the liquid crystal resulting in objectionable visible motion artifacts when displaying motion images.
Flat panel displays based on electromechanical light modulators have been proposed as a viable alternate to LCDs. One type of prior art electromechanical light modulator comprises of a light shutter plate attached to flexible members and both are constructed on a planar surface. A comb drive or similar electrostatic actuator is used to move the shutter plate in a plane parallel to the underlying substrate to modulate light.
In prior art designs the shutter plate is susceptible to tilting and touching the underlying substrate. Also electrostatic efficiency of actuators used to move the shutter plate is low. In prior art actuators, only a small surface defined by the thickness of the film is effective for generating electrostatic force.
Also LCD backlights generally do not meet the requirements for illuminating electromechanical light modulators. Using a LCD backlight with electromechanical light modulators will yield similarly low light efficiency of LCDs.